The wheels of rail-bound vehicles are provided with special wheel profiles along their circumferences, in order to fit the rail. The circumference of the wheel comprises a treading bearing on the rail and a flange projecting inside the rail in order to hold the rail-bound vehicle onto the rail. The wheels of the rail-bound vehicle are usually arranged in pairs, and the two wheels in one wheel-pair are rigidly connected with each other by a wheel-shaft. The two wheels of a wheel-pair thus usually rotate with the same rotation velocity.
Damages on a wheel may cause damages on the rail or may cause the rail-bound vehicle to go off the rail. The vehicle must therefore be taken to a repair shop in which the vehicle is lifted, after which the wheel-pair with the damaged wheel is replaced. The removed wheels may then be turned in a lathe so that the wheel profile once again becomes correct.
Document U.S. Pat. No. 4,276,793 shows a lathing device arranged to turn a wheel without prior removal of the wheel. The vehicle is lifted slightly so that the wheel can rotate and the lathing equipment is positioned beneath the vehicle in a pit under the rail. Due to the weight of the vehicle, having an axle pressure of about 25 ton, the device is very large and heavy and can only be provided in a repair shop. This is a problem since wheel-bound vehicles are often damaged when the vehicle is out in the field, wherein the vehicle can become stranded. Mobile lifting cranes has therefore been conceived for lifting the vehicle and changing a wheel-pair out in the field. However, modern cargo wagons are not built to be lifted while loaded, wherein for example a cargo wagon first needs to be emptied before the wagon can be lifted by the crane. Thus the time for a stand still becomes very long.
Trials have been made to manufacture lathing devices adapted for turning railroad wheels while the wheel remains on the vehicle and when the vehicle remains out in the field. One problem with such lathes and lifting devices is that it must be possible to fit the devices underneath the vehicle. A further problem is that some kind of reference for the turning of the wheels is needed.
One example of a device addressing these problems is shown in WO 2008/002261 showing a combined turning and lifting device. The device comprises a wedge pushed underneath the wheels for lifting the wheels from the rail. The wedge further comprises a roll adapted to make contact with the wheel, so that the wheel may be rotated and turned while standing on the wedge. One problem with this device is that if the wheel is heavily damaged vibrations will be created in the wheel when the roll encounters the damaged area. Hence variations will be introduced during the turning of the wheel meaning that the required tolerances may not be met. Another drawback with this device is that the roll-bearings must be very large in order to withstand the weights of heavy rail-based vehicles, such as cargo-wagons.